This invention relates to the art of blindstitch hemming; that is, the formation of stitches securing a hem fold in place in such fashion that the noticeability of the stitches on the face of the fabric is minimized.
Specialized commercial sewing machines have long been known for sewing true blind stitches. Since these machines can be used for no other purpose, they are not practical or economically feasible for houshold use.
The blindstitching arrangements which have heretofore been available for use with household sewing machines have required such tedious and skillful work manipulation as to render such arrangements impractical for use by most household sewing machine users. These prior arrangements such, for instance, as that disclosed in the U.S. Pat. No. 2,627,239 do not provide for stitching completely hidden from the fabric face but instead seek to minimize the appearance of the stitches on the fabric face. In the U.S. Pat. No. 2,627,239, the appearance of the stitches on the fabric face is minimized by use of a complicated Z shaped fold of the hem together with use of a special zigzag stitch pattern which shifts the needle only periodically into a position for penetration of the face ply of the fabric and at other times locates the needle to one side where it does not form hem securing stitches but places a line of connecting stitches in the unexposed portion of the hem fold.
It is very difficult to direct the Z shaped fold of goods to the sewing machine needle in such a way that during the infrequent lateral excursions of the needle, the needle merely grazes the edge of the upper fold edge. This is particularly true since for most of the stitches in the pattern, the needle occupies a different lateral postion. To simultaneously give concern to preserving the total width of the hem fold while carefully guiding the edge of the top fold requires a level of skill which most household sewing machine users do not possess.